One major function of the cerebellum is to dynamically adjust the relative motion of multiple joints and limbs, making movement smooth and accurate. To do this, cerebellar circuits must process complex temporal and kinetic relationships between body segments predictively, avoiding inaccuracies caused by long feedback delays. Cerebellar control processes must also be continually calibrated via adaptive mechanisms in order be useful in a constantly changing environment. It is clear that cerebellar damage disrupts practice-dependent adaptation of many movements. The implication of these studies is that standard practice of affected movements will provide minimal benefit for people with cerebellar damage. Yet, rehabilitation training is the main, if not only treatment for most cerebellar conditions. Little evidence exists on the effectiveness of rehabilitation training, though it may improve some aspects of movement control;the mechanisms for this are unclear. Therefore, we think that an increased understanding of the adaptation capacity in people with cerebellar damage may facilitate the optimization of rehabilitation techniques. We will test: 1) if there are maneuvers that can improve movement performance of people with cerebellar damage, 2) if adaptive capacity can be enhanced in people with cerebellar damage, and 3) if adaptive capacity predicts rehabilitation outcome (i.e. learning). We hypothesize that we may be able to enhance residual cerebellar function and/or tap into extra-cerebellar mechanisms to improve movement performance and adaptation capacity. We also hypothesize that adaptive ability will correlate with learning capacity in this population, allowing us to predict who will best respond to rehabilitation. As we perform these studies, we will evaluate different theories of cerebellar function (e.g. dynamics control, timing), by determining which aspects of movement performance and adaptation are most compromised in cerebellar patients. Thus, this work will test motor control theories while at the same time evaluating new strategies for rehabilitation. Lay summary: The cerebellum is a part of the brain important for coordination and learning of new movements through practice. In these experiments, we will work to understand how to improve movement coordination and motor learning abilities of people with cerebellar damage. We will also study the effects of a rehabilitation program designed to improve balance and walking.